xmonad 0.4 has been released. "xmonad is a tiling window manager for X. Windows are arranged automatically to tile the screen without gaps or overlap, maximising screen use. Window manager features are accessible from the keyboard: a mouse is optional. xmonad is written, configured and extensible in Haskell. Custom layout algorithms, key bindings and other extensions may be written by the user in Haskell, in config files. Window layouts are applied dynamically, and different layouts may be used on each workspace. Xinerama is fully supported, allowing windows to be tiled across several physical screens."

Yeah, I didn't find a package for Ubuntu, but it's easy to install with instruction from the page. There's just one trick to it: to add xmonad to Gdm options (the login screen), you'll want to make the file /usr/share/xsessions/xmonad.desktop .
Mine looks like:

I use this on FreeBSD on my laptop every day and it's great. Very easy to customize, lots of screen space... Pretty much everything you'd ever want. And using it on a laptop is especially handy since mousing is much more work.

I (and probably its not only me) spend too much time finding, unminimizing (uniconizing or whatever), moving, rearranging windows. These unorthodox keyboard-controled window managers can help solve this issue - they place the windows perfectly and you don't need to hunt windows with your mouse. And the best thing is that you have plenty of choice! You have wmii, ratpoison, xmonad and Ion. I think that computers must improve life by both making things easier and aiding you to think differently. Traditional WM's do not do that - they just emulate the real world desk: http://toastytech.com/guis/desk.html